In heat assisted magnetic recording (HAMR), information bits are recorded on a data storage medium at elevated temperatures. The data bit dimension can be determined by the dimensions of the heated area in the storage medium or the dimensions of an area of the storage medium that is subjected to a magnetic field. In one approach, a beam of light is condensed to a small optical spot on the storage medium to heat a portion of the medium and reduce the magnetic coercivity of the heated portion. Data is then written to the reduced coercivity region.
One example of a recording head for use in heat assisted magnetic recording includes a near field transducer (NFT) that is capable of focusing light to a spot size smaller than the diffraction limit. The NFT is designed to reach local surface-plasmon resonance at a designed light wavelength. At resonance, a high electric field surrounding the NFT appears, due to the collective oscillation of electrons in the metal. A portion of the field will tunnel into a storage medium and get absorbed, raising the temperature of the medium locally for recording.
The NFT's temperature significantly increases at plasmonic resonance. In addition, a portion of the NFT may be exposed at the air bearing surface of the recording head and is thus subject to mechanical wearing. NFT performance is greatly influenced by the heat and mechanical stress during HAMR operation. It would therefore be advantageous to have NFT devices that are more durable.